Mechanical tube expander

ABSTRACT

A mechanical tube expander including a cage having rollers mounted therein and a tapered mandrel to coact therewith for expanding the tube. A locking member permits movement of the mandrel a predetermined distance after the rollers make initial contact with the inner surface of the tube, thereby causing a predetermined expansion of the tube.

ilnited Mates Patent @lliver [4 Jan. m, 1.972

[54] MECHANICAL TUBE EXPANDER [72] Inventor: Richard M. Oliver,Chattanooga, Tenn.

[73] Assignee: Combustion Engineering, line, Windsor,

Conn.

[22] Filed: Dec. 29, 1969 [21] Appl. No.: 888,785

[52] US. Cl. ..72/393, 72/120, 72/399 [5 1] int. Cl ..B21d 41/02 [58]Field of Search. ..72/393, 399, 400, 370, 77, 72/78, 113, 120; 29/523[56] References Cited UNITED STATES PATENTS 2,736,950 3/1956 Mathews..29/523 3,247,695 4/1966 Linthicum et al ..72/370 2,405,399 8/1946 Bugget al ..29/523 2,737,996 3/1956 Toth 2,393,283 l/l946 Boyles et al..29/523 Primary Examiner-Charles W. Lanham Assistant Examiner-Michael JKeenan Attorney-Carlton F. Bryant, Eldon H. Luther, Robert L. 01- son,John F. Carney, Richard H, Berneike, Edward L. Kochey, Jr. and LawrenceP. Kessler {57] ABSTRACT A mechanical tube expander including a cagehaving rollers mounted therein and a tapered mandrel to coact therewithfor expanding the tube. A locking member permits movement of the mandrela predetermined distance after the rollers make initial contact with theinner surface of the tube, thereby causing a predetermined expansion ofthe tube.

4 Claims, 3 Drawing Figures PATENTEU JAN 18 1972 N llullm 2 m NI W7. W MW H m R IIIIIA \9 M NN NN 0w 0 nah/d! Q 0 m 3 WEI ATTORNEY MECHANICALTUBE EXPANDER BACKGROUND OF THE INVENTION Mechanical tube expanders havebeen used for some time to expand tubes into good physical contact withtube sheets. One problem that has always existed in tube expanders is inexpanding the tubes sufficiently to obtain the desired contact betweenthe tube and tube sheet, while preventing overexpansion which can damagethin wall tubes. This problem is particularly troublesome because of theinconsistencies in tube inner diameters.

SUMMARY OF THE INVENTION The tube expander of the present inventionmakes use of releaseable locking means and a spring having a givenamount of compression, which members coact with a tapered mandrel and acollar means which abuts a tube end, for causing expansion of the tube apredetermined amount. Thus regardless of the original inner diameter ofthe tube, it is always expanded a predetermined amount, substantiallyalleviating the problem of overexpansion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section of a tubeexpander at the start of an expanding operation;

FIG. 2 is a cross section of the tool at the completion of an expandingoperation; and

FIG. 3 is a sectional view of the gripping mechanism taken on line 3-3of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Looking now to FIG. 1, numeraldenotes a mechanical tube expander having a tapered mandrel 12. Mandrel12 extends through a cage which houses a plurality of rollers 16. As themandrel moves longitudinally through the cage 14 from right to left asshown in FIG. 1, the increasing diameter of the mandrel moves therollers radially outward, until they contact the inner surface of a tube17 which is to be expanded into good physical contact with a tube sheet19.

A collar 18 determines how far into the tube 17 the cage and itsassociated rollers extend. A thrust bearing 20 permits rotation of thecage 14 during the expanding operation, while permitting the collar 18to remain stationary. Rotation of the collar 18 during the expandingoperation could cause scarring of the tube end and tube sheet againstwhich it abuts, and would be undesirable. The above-described structureis old, and operates in the same manner as other mechanical tubeexpanders presently being used. A suitable pneumatic, hydraulic, orelectric motor (not shown) is attached to the right end 24 of mandrel 12to cause rotation thereof.

The novel apparatus of the invention which causes a predetermined amountof expansion of the tube 17 will now be described. A quick releasesleeve 26 surrounds the mandrel 12 rearwardly of the collar 18. Thissleeve 26 has a tapered or conical inner surface which acts as a wedge.Integral with sleeve 26 is a hand ring 27. Positioned inside of sleeve26 is a cylindrical member 28, which acts as a housing for a pair oflocking or gripping lugs 30. Integral with housing 28 is a thumb ring22. The lugs 30 extend through slots (see FIG. 3) cut through thehousing 28 so that their grooved inner surfaces can engage and interlockwith the grooves 32 on the surface of the mandrel 12 when they are movedinwardly by the tapered surface of sleeve 26. This locking position isshown in FIG. 2. Two pairs of springs 34 and 35 bias the lugs 30outwardly away from contact with the grooves 32 which is the positionshown in FIG. 1.

A spring 36 biases the quick release sleeve 26 and thumb ring 22 apart.Positioned intermediate the collar 18 and cylindrical member 28 is aspacer spring 38. On the left end of spring 38 a spring seat 40 islocated. Seat 40 has a cylindrical extension 41, the purpose of whichwill be later described.

LII

The operation of the tube expander will now be described. When it isdesired to expand a tube, the operator inserts the cage 14 into the boreof the tube 17, until collar 18 contacts the tube and tube sheet. Theoperator then grasps the thumb ring 22 and hand ring 27, moving themtogether, causing compression of spring 36. Springs 34 and 35 thus causethe locking lugs to move outwardly away from the grooves 32 on themandrel 12, as the release of the wedging action of the quick releasesleeve 26 permits. Mandrel 12 is now free to be moved longitudinally ofall of the members surrounding it, including the cage 14, collar 18, andcylindrical member 28. Mandrel 12 is then moved into the tube 17 untilthe tapered portion thereof causes the rollers 16 to be moved outwardlyinto contact with the inner surface of the tube.

The operator then moves the quick release sleeve 26 and housing 28 bymeans of their associated rings 27 and 22 to the left with respect tothe mandrel, until spring seat 40 abuts against collar 18 and the rightend of spring 38 just touches and abuts against cylindrical member 28.Spring 38 should be stiff enough so that it will not be compressedunless some degree of force is exerted. The operator then releases ring27. Spring 36 thus causes ring 27 and its integral quick release sleeve26 to move to the left. The wedging action on gripping lugs 30 causesthem to move inwardly into a gripping or looking relationship withgrooves 32. The tube expander is now ready to cause expansion of thetube 17.

The drive motor for the tool is actuated at this time, causing rotationof the mandrel, which in turn causes rotation of the rollers 16 and theroller cage 14. The rollers 16 to mandrel 12 axial relationship isskewed 1 to 3 degrees which is well known in the industry as aself-feeding expander. Rotation of the mandrel 12 causes said mandrel tofeed inwardly to the left, the rollers 16 thereby being moved radiallyoutward to expand the tube 17. Because of the positive wedging orlocking action between lugs 30 and grooves 32 the cylindrical member 28moves along with the mandrel 12. Continued rotation of the mandrel 12causes continued longitudinal travel of the mandrel l2 and cylindricalmember 28 which causes compression of spring 38. The longitudinalmovement of the mandrel 12 and member 28 continues until the end ofcylindrical member 28 makes contact with the end 41 of the spring seat40. This condition of the tool is shown in FIG. 2. No furtherlongitudinal movement of the mandrel is possible at this time.

From the above, it can be seen that the mandrel 12 can move only apredetermined longitudinal distance D" after the rollers 16 initiallytouch and make contact with the inner surface of tube 17. Since themandrel has a fixed angle of taper throughout its tapered lengthportion, the rollers 16 will be cammed outwardly a fixed given amountdue to the movement of the mandrel, causing the tube 17 to be expanded apredetermined amount.

Although in the preferred illustrated embodiment spring seat 40 with acylindrical piece 41 is used as the stop member for abutting against theend of member 38 at the end of the expanding operation, this membercould be eliminated. If this were done, the spring 38 would have to befully compressed before longitudinal movement of the mandrel 12 werestopped. In this instance, the predetermined distance the mandrel wouldmove during the expansion operation would be determined by thedifference in length of spring 38 in its uncompressed and fullycompressed state.

From the above, it can readily be seen that the tube expander of thepresent invention can be used by even a relatively inexperiencedoperator to cause a predetermined amount of tube expansion time aftertime. Tolerance is very good. For example, if the grooves 32 are1/32-inch apart, and 1/16 inch of longitudinal travel of the mandrelcauses a 0.00l-inch tube expansion by the rollers 16, the tolerance willbe plus or minus 0.0005 inch of the desired expanded tube diameter. Thepredetermined amount of tube expansion can be readily and easily changedby using different sized spacer springs.

What is claimed is:

1 A tube expander including a tapered mandrel, a cage with radiallymovable rollers mounted therein surrounding the mandrel, which rollersmove outwardly as the tapered mandrel moves longitudinally therethrough,collar means surrounding the mandrel rearwardly of the cage and adaptedto abut against the end of the tube to be expanded, gripping meanssurrounding the mandrel rearwardly of the collar means, spring meanspositioned between the collar means and the gripping means and adaptedto abut against the end of each, said gripping means having a firstposition which permits longitudinal movement of the mandrel with respectthereto, and a second position in gripping contact with the mandrel, soas to move longitudinally therewith, whereby when a tube is to beexpanded the gripping means is originally maintained in its firstposition until the rollers contact the inner surface of the tube to beexpanded and the spring in its uncompressed state is in contact at oneend with the collar means and at its other end with the gripping means,at which time the gripping means is moved to its second position, andthe gripping means along with the engaged mandrel are movedlongitudinally with respect to the collar means a predetermined distanceuntil the spring has been completely compressed, thereby causing apredetermined amount of expansion of the tube.

2. The tube expander set forth in claim 1, wherein the gripping meansincludes lug means which are spring biased away from the mandrel, andwedge means for forcing the lug means into engagement with the mandrel.

3. The tube expander set forth in claim 2, wherein the lug means has agrooved surface which engages the mandrel, and the mandrel has grooveswhich coact with those on the lug means.

4. The tube expander set forth in claim 3, including means biasing thewedge means towards the position which forces the lug means intoengagement with the mandrel.

1. A tube expander including a tapered mandrel, a cage with radiallymovable rollers mounted therein surrounding the mandrel, which rollersmove outwardly as the tapered mandrel moves longitudinally therethrough,collar means surrounding the mandrel rearwardly of the cage and adaptedto abut against the end of the tube to be expanded, gripping meanssurrounding the mandrel rearwardly of the collar means, spring meanspositioned between the collar means and the gripping means and adaptedto abut against the end of each, said gripping means having a firstposition which permits longitudinal movement of the mandrel with respectthereto, and a second position in gripping contact with the mandrel, soas to move longitudinally therewith, whereby when a tube is to beexpanded the gripping means is originally maintained in its firstposition until the rollers contact the inner surface of the tube to beexpanded and the spring in its uncompressed state is in contact at oneend with the collar means and at its other end with the gripping means,at which time the gripping means is moved to its second position, andthe gripping means along with the engaged mandrel are movedlongitudinally with respect to the collar means a predetermined distanceuntil the spring has been completely compressed, thereby causing apredetermined amount of expansion of the tube.
 2. The tube expander setforth in claim 1, wherein the gripping means includes lug means whichare spring biased away from the mandrel, and wedge means for forcing thelug means into engagement with the mandrel.
 3. The tube expander setforth in claim 2, wherein the lug means has a grooved surface whichengages the mandrel, and the mandrel has grooves which coact with thoseon the lug means.
 4. The tube expander set forth in claim 3, includingmeans biasing the wedge means towards the position which forces the lugmeans into engagement with the mandrel.